Ali Tariq, Alwadie Abdullah S, Rizwan Abdul Rasheed, Sajid Ahthasham, Irfan Muhammad, Awais Muhammad
Electrical Engineering Department, College of Engineering, Najran University, Najran 61441, Saudi Arabia.
Department of Computer Science, Punjab Education System, Depaalpur 56180, Pakistan.
Sensors (Basel). 2020 May 18;20(10):2856. doi: 10.3390/s20102856.
The future of the Internet of Things (IoT) is interlinked with digital communication in smart cities. The digital signal power spectrum of smart IoT devices is greatly needed to provide communication support. The line codes play a significant role in data bit transmission in digital communication. The existing line-coding techniques are designed for traditional computing network technology and power spectrum density to translate data bits into a signal using various line code waveforms. The existing line-code techniques have multiple kinds of issues, such as the utilization of bandwidth, connection synchronization (CS), the direct current (DC) component, and power spectrum density (PSD). These highlighted issues are not adequate in IoT devices in smart cities due to their small size. However, there is a need to design an effective line-code method to deal with these issues in digital IoT-based communication for smart technologies, which enables smart services for smart cities. In this paper, the Shadow Encoding Scheme (SES) is proposed to transmit data bits efficiently by using a physical waveform in the smart cities' ecosystem. SES provides a reliable transmission over the physical medium without using extra bandwidth and with ideal PSD. In it, the shadow copy of the repeating bitstream is forwarded, rather than repeating the actual stream again and again. The PSD is calculated with the help of mathematical equations to validate SES. MATLAB simulator is used to simulate SES and compared with other well-known digital line-code techniques. The bit error rate is also compared between SES and the chirp spread spectrum (CSS) for the specific data frames. The coordinates of the PSD graph are also shown in tabular form, which shows a vivid picture of the working conditions of various line codes.
物联网（IoT）的未来与智慧城市中的数字通信相互关联。智能物联网设备的数字信号功率谱对于提供通信支持极为关键。线路编码在数字通信中的数据比特传输中起着重要作用。现有的线路编码技术是为传统计算网络技术和功率谱密度而设计的，用于使用各种线路码波形将数据比特转换为信号。现有的线路编码技术存在多种问题，如带宽利用率、连接同步（CS）、直流（DC）分量和功率谱密度（PSD）。由于其尺寸较小，这些突出问题在智慧城市的物联网设备中并不适用。然而，需要设计一种有效的线路编码方法来处理基于数字物联网的智能技术通信中的这些问题，从而为智慧城市提供智能服务。本文提出了阴影编码方案（SES），通过在智慧城市生态系统中使用物理波形来高效传输数据比特。SES在不使用额外带宽且具有理想PSD的情况下，在物理介质上提供可靠传输。在该方案中，转发的是重复比特流的影子副本，而不是反复重复实际流。借助数学方程计算PSD以验证SES。使用MATLAB模拟器对SES进行仿真，并与其他知名数字线路编码技术进行比较。还针对特定数据帧比较了SES与线性调频扩频（CSS）之间的误码率。PSD图的坐标也以表格形式呈现，展示了各种线路编码工作情况的清晰画面。
